Apex domains cannot have CNAME records.
Question and response
Question
dig awsdns-13.com. NS
Answer
awsdns-13.com. 5 NS g-ns-1741.awsdns-13.com.
awsdns-13.com. 5 NS g-ns-14.awsdns-13.com.
awsdns-13.com. 5 NS g-ns-589.awsdns-13.com.
awsdns-13.com. 5 NS g-ns-1165.awsdns-13.com.
Authority
The response has no authority records.
Additional
g-ns-14.awsdns-13.com. 5 A 205.251.192.14
g-ns-589.awsdns-13.com. 5 A 205.251.194.77
g-ns-1165.awsdns-13.com. 5 A 205.251.196.141
g-ns-1741.awsdns-13.com. 5 A 205.251.198.205
g-ns-14.awsdns-13.com. 5 AAAA 2600:9000:5300:e00:0:0:0:1
g-ns-589.awsdns-13.com. 5 AAAA 2600:9000:5302:4d00:0:0:0:1
g-ns-1165.awsdns-13.com. 5 AAAA 2600:9000:5304:8d00:0:0:0:1
g-ns-1741.awsdns-13.com. 5 AAAA 2600:9000:5306:cd00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0